Polymers of vinyl monomers that are useful, for example, as adhesives can be produced by bulk free-radical polymerization in a batch reactor under essentially adiabatic reaction conditions (see, for example, U.S. Pat. No. 5,986,011). In some situations, it can be advantageous to add solvent to the batch. For example, solvents can be utilized to reduce the heat load in the batch, or to reduce the viscosity of the polymer at the end of the polymerization to facilitate draining or subsequent processing. Typically, any solvent utilized must be removed from the polymer product. For example, after the reaction mixture is drained, an apparatus such as an extractor-extruder can be used to strip any solvent that was added to the batch. Solvent handling can also be expensive because extra equipment may be necessary to capture the solvent for reuse, or other capture methods such as a thermal oxidizers may be required to prevent the solvent from being vented to the atmosphere.
Often, molten polymer product is further processed (for example, to reduce brittleness or increase tackiness) in order to make the product more suitable for its end use by mixing in additives such as plasticizers and tackifiers, for example, while extruding the polymer.